For each tracer, two images are delivered. One is not corrected for the primary beam, while the other image is corrected for the primary beam (labeled with 'pbcor').
Images not corrected for the primary beam are typically used for mapping structure, while those corrected for primary beam are typically used for measuring accurate fluxes.

The format for each image data cube in a MASSES dataverse is:
[targetname].[configuration].[linename].cube.fits
[targetname].[configuration].[linename].cube.pbcor.fits

The format for each continuum image in a MASSES dataverse is: 
[targetname].[configuration].cont[wavelength].fits
[targetname].[configuration].cont[wavelength].pbcor.fits

In the first MASSES data release (Stephens et al. 2018), the SMA configuration is in the subcompact (sub) array. The delivered spectral lines are 12CO21, 13CO21, C18O21, and N2DP. High velocity CO (highvelCO) is delivered for ASIC data. The continuum is at 1.3 mm.

For Per-emb-38, there is a single track taken with the SWARM correlator: 170121
To import a fits image into miriad, the "fits" task should be used. "op=xyin" should be specified. We show an example for CO(2-1) below:
fits in=Per38.sub.12CO21.cube.fits out=Per38.sub.12CO21.cube op=xyin

While casa can directly handle fits image files, to import the file into casa format, the task importfits can be used:
importfits(fitsimage="Per38.sub.12CO21.cube.fits",imagename="Per38.sub.12CO21.cube")
